1. Field of the Invention
The present invention concerns a system for the display of color images on a matrix display panel, for example, a liquid crystal display panel. The invention is concerned more especially with the display of synthetic images but also applies to images from video image sensors such as, for example, vidicon cameras.
The invention relates more especially to an image processing system suited to display on a matrix display panel. This special type of processing produces a first function for smoothing and softening contours without any loss in addressability and, also, homogenization of the spatial distribution in the screen. The result of this is an improvement in image quality and visual comfort for the observer.
2. Description of the Prior Art
One of the problems encountered with matrix display panels relates to the restitution of synthetic images or images coming from video sensors on these discretized structures.
These screens consist of a matrix of elementary points which can be addressed individually by two orthogonal arrays of electrodes respectively corresponding to rows and columns. A liquid crystal display panel, for its part, is sandwiched between two arrays of electrodes. Furthermore, colored filters separated by opaque strips are placed on the display side to obtain the basic colors, red, green and blue abbreviated as R, G and B. An RGB trio corresponds to a color point. It is necessary to distinguish the image point, corresponding to an item of information which comes from the image generator (graphic processor or sensor) and may or may not be stored in an image memory, from the elementary point of the screen which is most often called a pixel and corresponds to the smallest addressable unit of the screen. A trio thus comprises three pixels.
As a rule, the size of a pixel is smaller than the eye's separating capacity: it then becomes necessary to consider no longer an elementary point or pixel but a region consisting of a set of these juxtaposed points.
The invention applies to this mode of observation of the screen according to which the elementary point of the screen is replaced by a small region, called a "micro-region" corresponding to the visual performance of the observer and, hence, to his perception of the image.
The micro-region is characterized by several parameters, essentially its position, shape, luminosity, color, the arrangement of the colored pixels, etc.
A given image may thus be considered to consist of a set of micro-regions with characteristics that may vary as a function of various parameters, such as: the nature of the plotting (line, color range, colored surface, alphanumerical character, etc.), elements coming from an image sensor etc.
The method used, therefore, makes it possible to adapt the restitution of the image as a function, especially, of the nature of the image (whether it is a synthetic image or one coming from a sensor), the type of matrix display, the distribution of the color pixels (whether tripled or quadrupled), faults in the screen and the conditions under which the image is observed (day or night).
Another object of the invention is to obtain half tones (also called grey tones).